Defects in glass bottles are often mold related. For this reason, it is useful to have a system which can identify which of a plurality of molds produced a particular bottle. The defective mold may then be shut down while the remaining molds continue to operate. Alternatively, the defective bottles may be automatically rejected as they proceed down the production line.
Mold identification is generally accomplished by molding a particular code into each bottle during the forming process. The code is later read by a scanner, which identifies the defective mold. Another method is to mark bottles produced by a particular mold, which allows for later identification and separation, as shown in U.S. Pat. No. 4,004,904. This system has the disadvantage of requiring that the bottles be in a particular sequence in order to allow proper marking of mold origin.
Several techniques have been developed for encoding a bottle and for reading the code. In U.S. Pat. No. 3,745,314, a bottle is held stationary while an image of a code molded into the bottom of a bottle is rotated past a reading station. The major disadvantage of this design is that the bottle must be at a standstill while the code reading is taking place, thus slowing down the production line process. In U.S. Pat. No. 3,963,918, a bottle with a circular code is brought to a standstill, and the code is read either by rotating the bottle or the reading receiver. This has the similar disadvantage of having to stop the bottle. U.S. Pat. No. 3,991,883 does not require bringing the bottle to a standstill, but still requires relative rotation between the bottle and the light source which is utilized to project the coded information onto the reading apparatus. A further disadvantage of all of the above-named inventions is that they employ a circular code, whose validity may be checked only by making successive readings of the code.
A principal advantage of the present invention is that no relative rotation between the bottle and the reading device or light source is required, thus simplifying operation.
Another advantage of the present invention is that readings may be taken simultaneously in several areas of the bottle in order to check the validity of the code reading, thus increasing the accuracy of mold identification.